Full text loading...
(a) Schematic side view of the external cavity laser with off-band surface-emitting Bragg grating coupler; (b) Schematic top view of the device (the drawing is not to scale); (c) SEM image of the gratings.
Bottom: Laser wavelength tuning spectra obtained by tilting the mirror angle; a few angle values are shown. Top: Calculated atmospheric transmission for a distance comparable with the laser cavity roundtrip in air, showing strong water absorption. Wavelength tuning measurements were conducted within the water vapor windows.
Fine wavelength tuning behavior as a function of the surface-emitting Bragg grating injection current. The top axis shows the grating peak current, the bottom shows its pulse energy. Open circles: gain current and grating current applied simultaneously. Filled square: was delayed by . Inset: examples of fine-tuning spectra.
External cavity laser power and wavelength control by combining gain and the Bragg grating (BG) segment currents. Filled squares: power variation as wavelength was tuned with BG segment alone. Open squares: Power corrected (maintained constant) with a gain current correction. Varying the power via the gain segment alone also resulted in unwanted wavelength shift (filled circles), which can be corrected with the BG current for constant wavelength (open triangles).
Article metrics loading...